In quarries and other types of payload material collection sites, mobile loaders, such as wheel loaders, backhoe loaders, and track type loaders are used to load loose payload material into haul vehicles, such as over the road trucks. Payload information, including the desired type and amount of payload material for each truck needs to be communicated to the quarry personnel who operate the loaders. For instance, this information might be transmitted from a quarry office based computer to a mobile computer on the loader via wireless communication as described in co-owned U.S. Pat. No. 5,848,368. This information enables the loader operator to proceed to the correct pile corresponding to the requested material.
A typical work cycle can begin with the operator first positioning the bucket of the loader at a pile of the requested material. The bucket is then lowered so that the work implement is near the ground surface. The operator then advances into the pile and controls the bucket to raise the work implement through the pile to fill the bucket and lift the material. The operator then tilts or pitches the bucket back to capture the material. The operator then moves the loader to a desired target location, such as an over the road truck, and dumps the captured material from the bucket. The operator then moves the loader back to the pile to start this work cycle over again. In the case of typical over the road trucks, depending upon their size, a full load will typically require between three and six bucket loads to fill the truck with the desired material up to a target load weight.
Many of today's loaders have payload control systems that allow for accurate measurements of the bucket payload. Thus, with each successive bucket, the loader can sum the load weight of the bucket loads to determine an estimated amount of payload already in the truck. Typically on a final pass of the truck loading cycle, the loader operator loads, weighs, and manually discards excess material to achieve the desired truck target payload weight. This process of manually discarding excess material is time consuming and wasteful since it requires trial and error weigh cycles. In the case of a typical over the road truck with a target load capacity of about 45 tons, it is difficult for even skilled operators to place an amount of material in the truck that is within 1,000 pounds of that target load, but without exceeding the target payload. Less skilled operators require substantially more time through trial and error to fully load a truck without exceeding the target weight, while still being acceptably close to the target payload weight.
After the truck has been loaded, to determine if the truck has been loaded with a desired amount of payload material, the truck is usually driven onto scales and weighed before leaving the quarry or other payload collection site. If the truck is overloaded, some of the payload material must be removed. Alternatively, if the truck is substantially underloaded, more payload material must be added. These processes cost additional time and money.
One strategy for dealing with these precision loading problems is described in co-owned U.S. Pat. No. 6,211,471. In that reference, the loader payload control logic determines that a final pass is needed to bring the truck payload up to a target payload weight. The control logic then controls the loader and implement actuators to retrieve and capture the desired weight of material into the bucket from the pile. The material is then dumped into the truck to bring it up to its desired target weight. Thus, this strategy seeks to retrieve a precise weight of material with the bucket from the pile using control logic, and then dump the entire contents of that partial bucket load into the truck. While this strategy appears to have promise, in practice there is great difficulty in precisely loading a desired weight of material in a bucket, as many variables contribute to, or detract from, the ability to accomplish this task on a reliable and repeatable basis.
The present disclosure is directed to overcoming one or more of the problems set forth above.